calc++: don't rely on Automake to compile a C++ parser.
Basically, revert commit
609b3d8096fb0cc1fa4d908b6e1a860ced260bda,
Automake 1.11.3 is not safe enough for C++ parser.
* examples/calc++/calc++-parser.hh: Remove.
* examples/calc++/local.mk (examples/calc++/calc++-parser.stamp):
New.
examples: factor the extractions into a single step
extexi had to be run in the extraction directory. Now, it can be
given the files with expected output directory. This allows to
use $(*_extracted) variables (before we had to list again their
members, but limited to their base names). In turn, this also
allows fusing the extraction recipes into a single one.
Also, it is currently too hard (or requires too much duplication,
since Make wants all the occurrences of the files to be prefixed with
$(srcdir)/, which is something Automake cannot support for *_SOURCES)
to work in the source tree. So extract, and compile scanners and parsers
in the build tree.
* examples/extexi (basename): New.
(BEGIN): Now "file_wanted" maps base name to extracted file name.
* examples/calc++/local.mk, examples/mfcalc/local.mk,
* examples/rpcalc/local.mk: Fuse extraction rules into...
* examples/local.mk: Here.
(extract, extracted): New.